Table 5 Mean (± SE) concentrations of selected plant macronutrients in onion leaves grown from soil amended with conventional fertilizer, compost, and compost + fertilizer during two growing seasons, Hidalgo County, Texas, 2009–2011 (n = 6 replications)

Control

Feb 2010

2.4 ± 0.2^b

6,951 ± 227^a

33,322 ± 1,459

14,618 ± 562a

2,172 ± 69

Fertilizer

3.0 ± 0.2^a

4,769 ± 320^b

29,479 ± 1,713

12,576 ± 585b

2,212 ± 43

Compost

3.0 ± 0.2^a

5,512 ± 442^ab

31,175 ± 646

12,566 ± 370b

2,141 ± 66

C + F^a

3.3 ± 0.1^a

4,859 ± 406^b

30,818 ± 750

12,545 ± 356b

2,142 ± 65

F^b

4.62

7.87

2.38

4.77

0.27

P

0.0193

0.0022

0.1105

0.0157

0.8469

Control

Mar 2011

1.8 ± 0.1^b

5,606 ± 127c

25,430 ± 4,609^b

15,096 ± 402^a

2,236 ± 44^b

Fertilizer

2.4 ± 0.1^a

7,195 ± 106^a

33,128 ± 1,431^ab

12,534 ± 192^b

2,362 ± 60^ab

Compost

2.4 ± 0.1^a

6,868 ± 252^a

33,584 ± 1,277^a

12,909 ± 454^b

2,415 ± 75^ab

C + F^a

2.4 ± 0.1^a

6,060 ± 257^a

34,135 ± 496^a

14,843 ± 390^a

2,580 ± 44^a

F^b

26.26

10.37

3.33

11.28

6.71

P

 < 0.0001

0.0006

0.0481

0.0004

0.0043